Century-old photos of the forests near Bend and Sisters show a patchwork of burned and unburned woods, the result of fires that were naturally caused and allowed to burn without human interference.

A century of fire suppression has dramatically changed the picture, however, leaving forests packed with fuel that can make natural fires far more extensive and dangerous.

As forest managers seek to restore the balance, they run into a peculiar problem: Federal law says we should leave designated wilderness areas alone, allowing nature to take its course. But the forests’ current condition is anything but natural, so the natural processes don’t work naturally.

Human interference is needed now to correct for human interference in the past.

That’s the argument for planned prescribed burns in wilderness areas of the Deschutes and Willamette national forests. Despite the apparent conflict in the idea of managing forests in the wilderness, it makes sense.

The U.S. Forest Service has chosen two wilderness areas for prescribed burns, one west of Bend along the Cascade Lakes Highway and another near Scott Mountain, southwest of Sisters along the McKenzie Highway.

The area along the McKenzie is in the Mount Washington Wilderness Area, and the fires could be set as early as this fall. The Cascade Lakes section is in the Three Sisters Wilderness Area, with action likely a year later in fall 2014.

Opposition is coming from environmental groups such as the Blue Mountains Biodiversity Project in Fossil, which says the plan violates the idea of wilderness and that the fires won’t burn the same way as ones that start naturally from lightning.

The Forest Service counters that forests need to be returned to a state where natural fires can be allowed to burn. They say they will start small, a couple of hundred acres at a time, in a process that will take 20 to 30 years to complete.

Extensive wildfires in recent years, in Oregon and other states, testify to the risks of inaction to address the legacy of misguided fire suppression in the past. The Forest Service is on the right track.